Low profile perfusion catheter

ABSTRACT

Disclosed is a Low Profile Perfusion Catheter, for use in coronary angioplasty applications. Preferably, the catheter is provided with an inflatable dilatation balloon, and a perfusion lumen extending therethrough. The diameter of the perfusion lumen is enlargable from a first, reduced diameter to a second, enlarged diameter. In one embodiment, an axially movable tubular support is movable within the lumen from a proximal, insertion position to a distal perfusion position. In another embodiment, the support is radially expandable. In a further embodiment, a porus drug delivery balloon is provided.

This application is a continuation of application Ser. No. 08/208,617,filed Mar. 8, 1994 pending, which is a continuation of application Ser.No. 08/084,820, filed Jun. 30, 1993, now U.S. Pat. No. 5,344,402, issuedSep. 6, 1994.

BACKGROUND OF THE INVENTION

The present invention relates to catheters for insertion into a bodylumen. More particularly, the present invention relates to a low profileballoon dilatation and/or drug delivery catheter, having a temporarystent for permitting perfusion while positioned within the vascularsystem.

A wide variety of catheters have been developed in the prior art forpercutaneous transluminal coronary or peripheral vascular applications.For example, balloon dilatation catheters for performing percutaneoustransluminal coronary angioplasty ("PTCA") are well known in the art.

In general, PTCA is one procedure for treating a narrowed region in anartery, which, in one form, uses a catheter having an expandable balloonthereon. The catheter is percutaneously inserted such as into thefemoral artery, and advanced transluminally until the dilatation balloonis positioned within the restricted portion of the lumen. The balloon isthereafter inflated to radially outwardly displace the obstruction torestore some or all of the original interior diameter of the lumen.

Since this treatment modality requires placement of the deflated balloonacross the lesion to be treated, the diameter of the insertion tip ofthe catheter and deflated profile of the balloon can be limitingfactors. This is true either for lesions located in particularly smalldiameter arteries, or larger diameter arteries having a lesion whichoccludes a relatively high percentage of the native diameter. Thus,efforts have been in the prior art to produce balloon dilatationcatheters having as small a deflated profile as possible.

Other developments in the art include modifying the methodology so thatthe dilatation balloon remains in an expanded state for a period of timelonger than the initial dilatation. Depending upon the medical conditionof the patient and clinical judgment, the inflatable balloon may remainin an expanded state for anywhere from several minutes to several hoursor longer. Unfortunately, the dilatation balloon necessarily occludesthe artery in which it has been expanded, giving rise to a risk ofischemic episodes to the downstream tissue even for relatively shortdilatations.

Thus, various efforts have been made in the prior art to produce aballoon dilatation catheter which has some provision for allowing bloodflow through or around the balloon during the period of time that theballoon is in the inflated state. Typically, these efforts include theprovision of a central through lumen within the balloon, having bloodinfluent ports on one side of the balloon and blood effluent ports onthe other side of the balloon. Unfortunately, while these developmentsmay improve the ability to leave the balloon in the dilated state forextended periods, they necessarily enlarge the deflated profile of theballoon catheter. As a result, access to either remote or highlyocclusive lesions is limited.

Thus, there remains a need for a catheter which has a minimal deflatedor insertion profile for permitting access to remote or highly occlusivelesions, and which at the same time permits sufficient perfusion tominimize the occurrence of ischemic episodes while the balloon isinflated.

SUMMARY OF THE INVENTION

There is provided in accordance with one aspect of the present inventiona balloon catheter, such as for performing balloon dilatation proceduresin a body lumen. The catheter comprises an elongate flexible tubularbody, having an inflatable balloon thereon. At least one influent portis provided on the body on a first side of the balloon, and at least oneeffluent port is provided on the body on a second side of the balloon.The influent and effluent ports are in fluid communication with eachother by way of a central lumen extending through the balloon. Anaxially movable support is positioned within the central lumen, suchthat the support is movable from a first, proximal position forinstallation of the catheter, to a second, distal position formaintaining patency of the central lumen and permitting perfusion whilethe balloon is inflated.

The central lumen has a first inside diameter when the support is in theproximal position, and a second, larger inside diameter when the supportis in the distal position. Preferably, the support comprises a springcoil.

In an over the wire embodiment of the invention, the tubular body isprovided with a guidewire lumen extending from a proximal guidewireaccess port to a distal guidewire opening an the tip of the catheter. Inanother embodiment of the invention, an access port is provided on theside of the tubular body for providing access to the guidewire lumen ata point in between the inflation balloon and the proximal end of thetubular body, to produce a monorail catheter.

In accordance with another aspect of the present invention, there isprovided a balloon catheter comprising an elongate flexible tubular bodyhaving an inflatable balloon thereon. The balloon is expandable from afirst, reduced diameter to a second, enlarged diameter.

A perfusion conduit extends through the inflatable balloon, and at leasta portion of the perfusion conduit is expandable from a first reduceddiameter to a second enlarged diameter. Preferably, the second, enlargeddiameter of the perfusion conduit is larger than the first, reduceddiameter of the inflatable balloon.

Preferably, a tubular support is additionally provided for maintainingthe perfusion conduit in the second, enlarged diameter. The support isin one embodiment disposed proximally of the balloon when the balloon isin the first, reduced diameter. The support is movable distally to aposition within the balloon to maintain the perfusion conduit in thesecond, enlarged diameter.

In another embodiment, the support is radially outwardly expandable froma first, reduced diameter, to a second, enlarged diameter. In thisembodiment, the support is expanded within the perfusion conduit tomaintain the perfusion conduit in the second, enlarged diameter tofacilitate perfusion such as during a dilatation procedure.

In accordance with a further aspect of the present invention, there isprovided a balloon catheter comprising an elongate flexible tubular bodyhaving a central lumen extending through at least a portion of the body.At least one influent port extends through the wall of the tubular bodyand communicates with the central lumen. At least one effluent portextends through the wall of the tubular body and also communicates withthe central lumen. The central lumen is expandable from a first, reducedinterior diameter to a second, enlarged interior diameter.

Preferably, a support is provided for maintaining the central lumen inthe second, enlarged diameter. The support in one embodiment is axiallymovable from a first, proximal position to a second, distal position,wherein at least the distal position is within the portion of thecentral lumen that extends through the balloon. Preferably, the supportcomprises a spring coil.

In another embodiment, the support is radially outwardly expandable froma first, reduced diameter to a second, enlarged diameter. Preferably,the support comprises a spring coil, and radial expansion isaccomplished by relative rotation of one end of the spring coil withrespect to the other end of the spring coil.

In accordance with a further aspect of the present invention, there isprovided a method of providing fluid flow from at least one influentport on a catheter, through a lumen in the catheter and out at least oneeffluent port on the catheter.

The method comprises the steps of providing a catheter of the typehaving an elongate flexible tubular body, at least one influent port onthe tubular body and at least one effluent port on the tubular body,said influent and effluent port in fluid communication with each otherby way of a central lumen extending through the body.

The catheter is positioned within a body lumen having a fluid therein,and the interior diameter of the central lumen is expanded from a first,reduced diameter to a second, enlarged diameter. Fluid is permitted toenter the influent port, travel through the central lumen in itsexpanded diameter, and exit the effluent port. Preferably, a support ispositioned within the central lumen to maintain the central lumen in thesecond, enlarged diameter. In one embodiment, the support is positionedwithin the central lumen by axially distally displacing a movabletubular support.

In accordance with a further embodiment of the present invention, a drugdelivery balloon is disposed over the inflation balloon. One or morespots or regions on the inflation balloon are secured to the deliveryballoon, so that reduction in the profile of the inflation balloon suchas by aspiration causes a reduction in profile of the outer deliveryballoon.

Further features and advantages of the present invention will becomeapparent to one of skill in the art in view of the Detailed Descriptionof Preferred Embodiments which follows, when considered together withthe attached drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a dilatation and temporary stentcatheter in accordance with the present invention.

FIG. 2 is a cross sectional view of the catheter taken along the lines2--2 in FIG. 1.

FIG. 3 is an enlarged cross sectional view through the lines 3--3 onFIG. 1.

FIG. 4 is an enlarged side elevational view of the distal end of thecatheter shown in FIG. 1, with the balloon illustrated in the deflatedposition and the movable support in the proximal position.

FIG. 5 is a side elevational cross sectional view of the distal portionof the catheter, showing the movable support in the proximal position.

FIG. 6 is a side elevational cross sectional view of the distal portionof the catheter, with the movable support in the distal position formaintaining patency of the central lumen within the balloon.

FIG. 7 is a side elevational view of the distal end of an alternateembodiment of the present invention, with the central lumen in acollapsed state.

FIG. 8 is a side elevational view of the embodiment of FIG. 7, shownwith the central lumen in the open state.

FIG. 9 is a side elevational view of a drug delivery catheter inaccordance with the present invention.

FIG. 10 is a cross sectional view along the lines 10--10 in FIG. 9.

FIG. 11 is a cross sectional view along the lines 11--11 in FIG. 9.

FIG. 12 is a cross sectional elevational view of the distal end of theembodiment of FIG. 9, shown with a tubular support in the insertionposition.

FIG. 13 is a cross sectional elevation view as in FIG. 12, with thetubular support in the perfusion position.

FIG. 14 is a cross sectional elevational view of an alternate tipembodiment of the invention, shown in the insertion configuration.

FIG. 15 is a cross sectional elevational view of the embodiment of FIG.14, shown in the perfusion position.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1, there is disclosed a combination dilatation andtemporary stent catheter 10 in accordance with one aspect of the presentinvention. In other aspects of the present invention, described infra, adrug delivery embodiment is additionally disclosed. Catheters embodyingany of the temporary stent, drug delivery and dilatation featuresdisclosed herein, or any combination of these features, will be readilyapparent to one of skill in the art in view of the disclosure herein.

The catheter 10 generally comprises an elongate tubular body 12extending between a proximal control end 14 and a distal functional end16. The length of the tubular body 12 depends upon the desiredapplication. For example, lengths in the area of about 120 cm to about140 cm are typical for use in percutaneous transluminal angioplastyapplications.

The tubular body 12 may be produced in accordance with any of a varietyof known techniques for manufacturing balloon-tipped catheter bodies,such as by extrusion of appropriate biocompatible plastic materials.Alternatively, at least a portion or all of the length of tubular body12 may comprise a spring coil, solid walled hypodermic needle tubing, orbraided reinforced wall, as is well understood in the catheter and guidewire arts.

In general, tubular body 12, in accordance with the present invention,is provided with a generally circular cross-sectional configurationhaving an external diameter within the range of from about 0.03 inchesto about 0.065 inches. In accordance with one preferred embodiment ofthe invention, the tubular body 12 has an external diameter of about0.042 inches (3.2 f) throughout most of its length. Alternatively, agenerally triangular cross-sectional configuration can also be used, aswell as other non-circular configurations, depending upon the method ofmanufacture and the intended use.

In a catheter intended for peripheral vascular applications, the body 12will typically have an outside diameter within the range of from about0.039 inches to about 0.065 inches. In coronary vascular applications,the body 12 will typically have an outside diameter within the range offrom about 0.030 inches to about 0.045 inches. Diameters outside of thepreferred ranges may also be used, provided that the functionalconsequences of the diameter are acceptable for the intended purpose ofthe catheter. For example, the lower limit of the diameter for tubularbody 12 in a given application will be a function of the number of fluidor other functional lumen contained in the catheter, together with theacceptable maximum flow rate of dilatation fluid or drugs to bedelivered through the catheter, and the desired structural integrity.

Tubular body 12 must have sufficient structural integrity (e.g.,"pushability") to permit the catheter to be advanced to distal arteriallocations without buckling or undesirable bending of the tubular body.The ability of the body 12 to transmit torque may also be desirable,such as in embodiments having a drug delivery capability on less thanthe entire circumference of the delivery balloon. Larger diametersgenerally have sufficient internal flow properties and structuralintegrity, but reduce perfusion in the artery in which the catheter isplaced. Increased diameter catheter bodies also tend to exhibit reducedflexibility, which can be disadvantageous in applications requiringplacement of the distal end of the catheter in a remote vascularlocation. In addition, lesions requiring treatment are sometimes locatedin particularly small diameter arteries, necessitating the lowestpossible profile.

The proximal end 14 of catheter 10 is provided with a manifold 18 havinga plurality of access ports, as is known in the art. Generally, manifold18 is provided with a guide wire port 20 in an over the wire embodimentand a balloon inflation port 22. Additional access ports are provided asneeded, depending upon the functional capabilities of the catheter.

The proximal end 14 of the catheter 10 is additionally provided with acontrol 24 for manipulating the axial position of the movable support50, as will be discussed infra. In the illustrated embodiment, control24 comprises an axially movable tubular sleeve 26, as will be discussedin connection with FIG. 3.

The distal end 16 of catheter 10 is provided with an inflatable balloon28, illustrated schematically in FIG. 1. One or more influent flow ports30 are positioned on the proximal side of balloon 28, for communicatingwith one or more effluent ports 32 positioned on the distal side of theballoon. The fluid flow direction between the influent port 30 and theeffluent port 32 can be readily reversed, as will be apparent to one ofskill in the art, depending upon the location of the site to be treatedand the direction of access to that site relative to the direction ofblood flow.

The distal end 16 of the catheter 10 is provided with an atraumaticdistal tip 34, usually having a guide wire exit port 36 as is known inthe art. Preferably, a radiopaque marker 38 is provided to facilitatepositioning of the catheter, as is known in the art. Suitable markerbands can be produced from a variety of materials, including platinum,gold, and tungsten/rhenium alloy.

The distal tip 34 preferably further comprises a distal introductionsegment 35 having an outside diameter within the range of from about0.020 inches to about 0.030 inches, and a length within the range offrom about 2 mm to about 5 mm. In one embodiment, the introductionsegment 35 of tip 34 has an outside diameter of about 0.026 inches, anda length of about 2.0 mm.

A perfusion segment 37 is positioned proximally of the introductionsegment 35, for carrying one or more effluent ports 32. The length anddiameter of perfusion segment 37 can be varied depending upon desiredflexibility and perfusion characteristics. In general, an outsidediameter within the range of from about 0.03 inches to about 0.04 inchesand a length of from about 5 mm to about 10 mm will be used. In oneembodiment, the diameter is about 0.033 inches and the length is about6.5 mm.

The number, size and position of effluent ports 32 can be varied widelywithin the scope of the invention. In general, the present inventor hasfound from about 2 to about 10 effluent ports 32 to be workable.Preferably, about six ports, each having a diameter of from about 0.014inches to about 0.021 inches, are used.

Effluent flow ports 32 are placed in fluid communication with the one ormore influent flow ports 30 by way of a central lumen 54, as will bediscussed infra. In general, central lumen 54 extends axially throughthe interior of the balloon 28, and also through the interior of themovable support 50 when it is in the distal position. See FIG. 6.

To accommodate the axial movement of the movable support 50 from aproximal, introduction position (FIG. 4) to a distal, perfusion position(FIG. 6), the tubular body 12 is enlarged at an influent region 39, aswill be detailed infra. The one or more influent ports 30 are positionedabout the periphery of the influent region 39 to permit fluidcommunication between the influent ports 30 and effluent ports 32through central lumen 54 when the movable support 50 is in the distalposition.

The total number, size and distribution of the influent ports 30 can bevaried considerably. In general, between about six and sixty influentports 30 are preferred and, in one embodiment, thirty influent ports 30are provided, each having a diameter within the range from about 0.014inches to about 0.021 inches.

The inflation and temporary stent catheter 10 can be constructed aseither an over-the-wire catheter or as a monorail catheter. In amonorail embodiment, the proximal guidewire port 20 can be deleted, anda guidewire access port (not illustrated) is provided at a point inbetween the balloon 28 and the manifold 18. Preferably, the guidewireport is positioned within the range of from about 10 cm to about 40 cmfrom the distal end of the catheter. More preferably, the guidewire portis positioned about 30 cm from the distal end. In general, the guidewireport can be positioned as proximally as desired, so long as it does notunduly interfere with the catheter exchange advantage of a monorailcatheter on the guidewire. The guidewire port can be positioned as fardistally as desired, so long as it does not interfere with the balloonand perfusion features of the catheter, and with the pushability of thecatheter on the guidewire.

The guidewire port in a monorail embodiment provides direct lateralaccess to the interior of guidewire lumen 42, so that a guidewire can beintroduced through the monorail port, distally through lumen 42 and outdistal guidewire exit port 36 as is known in the art. In a monorailembodiment, the elongate tubular body 12 can be formed in a mannersimilar to an over the wire embodiment, with guidewire lumen 42extending throughout the entire length of the tubular body. Preferably,a stiffening wire or other stiffening structure is positioned withinguidewire lumen 42 between the guidewire port and the manifold 18. Sucha stiffening wire improves the pushability of the catheter, as will beunderstood by one of skill in the art.

Alternatively, that portion of guidewire lumen 42 proximal to guidewireport can be deleted, provided that the polymer or other supportstructure in the tubular body 12 has sufficient structural integrity toaccomplish the desired result. In this embodiment, the catheter body 12is provided with two lumen (inflation and push wire) proximally of theguidewire port, and three lumen (inflation, push wire and guidewire)distally of the guidewire port. Additional through lumens, such as fordrug delivery, can also be provided as needed.

Referring to FIG. 2, the illustrated over the wire embodiment of tubularbody 12 comprises a guidewire lumen 42, a balloon inflation lumen 44,and a push wire lumen 46. In an embodiment of the catheter 10 having a0.042 inch outside diameter tubular body 12, the guidewire lumen 42preferably has a diameter of about 0.018 inches. The balloon inflationlumen 44 has a diameter of about 0.013 inches, and the push wire lumen46 has a diameter of about 0.015 inches.

An axially movable push wire 48 extends axially through push wire lumen46. Push wire 48 is connected at its proximal end to the control 24, andat its distal end to movable support 50. In the illustrated embodiment,push wire 48 comprises a solid core wire such as a stainless steel wirehaving a diameter of about 0.012 inches at its proximal portion and areduced diameter of about 0.006 inches for about the distal most 20centimeters. Preferably, at least the proximal, larger diameter portionof the push wire 48 is provided with a teflon coating or other coatingfor minimizing friction within the push wire lumen 46.

Push wire 48 is connected to the moveable support 50 by brazing,soldering or other techniques known in the art and appropriate for thematerials to be joined.

The proximal end 52 of push wire 48 can be secured to the push wirecontrol 24 in any of a variety of ways. In the embodiment illustrated inFIG. 3, proximal end 52 extends radially outwardly through an opening 55in tubular body 12, for connection to the push wire control 24. In thisembodiment, push wire control 24 comprises an axially movably disposedtubular sleeve 26 of heat shrink material, such as a polyolefin.

Alternatively, the tubular sleeve 26 may be made from any of a varietyof polymeric or metal materials, as long as a sufficient bond orinterlocking fit can be provided between the proximal end 52 of pushwire 48 and the material of the control 24. Slide switches, buttons orlevers may also be used. In practice, the connection between the sleeve26 and the push wire 48 should be sufficient to permit an axial distalmotion, as will be discussed infra, but the ability to axiallyproximally retract the push wire 48 and movable support 50 is notgenerally required.

Referring to FIGS. 4-6, the axially movable support feature of thepresent invention is disclosed. In general, the profile of the deflatedballoon limits the catheter's ability to treat lesions in small diameterbody lumen. For this reason, the outside diameter of the distal tip 34and deflated balloon 28 are optimally minimized. At the same time, inorder to permit extended periods of dilatation, a temporary stent orconduit is preferably provided to permit continued blood flow during thedilatation. This tends to require a central through lumen in theballoon, which increases the profile of the deflated balloon.

In accordance with the present invention, a movable support 50 isprovided, for defining a central lumen 54. The movable support 50 isaxially movable from a first, proximal position (FIGS. 4 and 5) to asecond, distal position (FIG. 6). While the support 50 is in theproximal position, the deflated balloon 28 has a minimal profile tofacilitate positioning adjacent an obstruction in a small diameterartery. Preferably, the deflated profile of the balloon is less thanabout 0.040 inches, and, more preferably, the deflated profile of a 3 mminflated diameter balloon is less than about 0.034 inches.

Following positioning of the balloon within a restricted portion of theartery, the movable support 50 is advanced distally to the secondposition within the balloon. In the illustrated embodiment, movablesupport 50 provides a central lumen 54 through the balloon 28 having aninterior diameter of about 0.039 inches, which is generally larger thanthe exterior deflated profile of the balloon when the support 50 is inthe proximal position.

The movable support 50 preferably comprises a support structure forresisting radial compression of central lumen 54 by the inflated balloon28. Suitable support structures include tubular bodies which maycomprise extrusions, braided or woven polymeric or metal reinforcementfilaments, or a spring coil 51. Spring coil 51 preferably comprises amaterial having suitable biocompatibility and physical properties, suchas stainless steel or platinum wire. Alternatively, polymeric materials,such as nylon or Kevlar (DuPont) may also be used. Preferably,rectangular ribbon is used, having cross-sectional dimensions on theorder of about 0.001 inches by about 0.003 inches for small vessels, andon the order of about 0.005 inches by about 0.010 inches for use inlarger vessels.

The wire or ribbon is preferably wound to produce a coil having aninterior diameter within the range of from about 0.030 inches (coronary)to about 0.100 inches (peripheral) and an exterior diameter within therange of from about 0.032 inches (coronary) to about 0.110 inches(peripheral).

Spring coil 51 may be either tightly wound (bottomed out) so thatadjacent loops of coil are normally in contact with each other, orloosely wound, as illustrated in FIGS. 5 and 6, in which the adjacentloops of coil are normally separated from one another. The selection ofa tightly wound or loosely wound coil for use in the present inventionwill be influenced by such factors as the desired weight of the finishedcatheter, the relative desired flexibility of the catheter in the regionof the movable support 50, and the amount of radially inwardly directedcompressive force exerted by the inflation balloon 28. Radiopacity mayalso be a factor.

Preferably, spring coil 51 is provided with an outer sheath or coating53. Sheath 53 may be produced by dipping, spraying, heat-shrinking orextrusion techniques, which are understood in the art, and preferablycomprises a relatively flexible material having sufficientbiocompatibility and relatively low friction at its contact surface withthe interior of the catheter 10. Suitable materials for sheath 53comprise linear low-density polyethylene, such as that produced by Dow,polyethylene teraphthalate, nylons, polyester or other known or laterdeveloped medical grade materials. In one embodiment, a polyethylenetube having a wall thickness of about 0.002 inches and native diameterof about 0.050 inches is positioned coaxially about a 0.043 inches O.D.spring coil and reduced in diameter by application of heat to produce atight fit over the spring coil.

A central cavity for receiving the moveable support 50 can be formed inany of a variety of ways. In accordance with one method of manufacturingthe catheter 10, approximately the distal most 5 centimeters of theguidewire lumen 42 are enlarged to an interior diameter of about 0.050inches by thermal blow molding the catheter body. The resultingthickness of the wall 13 is about 0.001 inches. In the illustratedembodiment, this enlarged diameter is maintained for approximately 4centimeters, at which point the distal tip assembly 34 is provided.

The flexibility of the tubular wall 13 extending through the interior ofballoon 28 permits the central lumen 54 to be collapsed to provide aminimal profile for insertion and positioning of the catheter. Followinginsertion of the catheter, tubular wall 13 can be reexpanded to itsoriginal interior diameter such as by fluid flow, or by positioning ofthe support 50 as described elsewhere herein. Patency of the centrallumen 54 through tubular wall 13 is thus restored by and/or maintainedby support 50.

Although the present description will periodically refer to a firstreduced diameter of the central lumen 54 and a second expanded diameterof the central lumen 54, that is intended to include also a firstcollapsed state and second open state. In general, the wall 13 comprisesa substantially inelastic material so that actual expansion of the wallis not ordinarily accomplished. The feature sought to be accomplished bythe collapsible wall 13 is a reduced exterior profile for insertion ofthe catheter, and a later increased fluid flow capacity through thecentral lumen 54 as will be apparent in view of the disclosure herein.

In general, it is desired that the ratio of the interior cross-sectionalarea of lumen 54 to the maximum exterior cross-sectional area of thedeflated balloon be maximized, in order to optimize perfusion throughthe balloon 28 while inflated. Catheters embodying the presentinvention, and having a cross-sectional profile through the stent 50 ofabout 0.055 inches (4.2 f) can be produced having a central lumen 54with an interior diameter of at least about 0.030 inches, and preferablyabout 0.039 inches or greater. This still fits readily within the lumenof a typical guide catheter, which may have an internal diameter ofabout 0.072 inches.

In one embodiment of the present invention, the interior diameter oflumen 54 is about 0.039 inches. This lumen will typically provide a flowat 80 millimeters Hg of approximately 50 milliliters per minute.Alternatively, the inside diameter of lumen 54 can be reduced to as lowas about 0.012 inches and still function as a guidewire conduit.

Dilatation balloon 28 generally comprises a proximal neck portion 60, adistal neck portion 62, and an intermediate dilatation portion 64. Theproximal neck portion 60 is conveniently extended for at least about 2to 3 centimeters in the proximal direction. In the illustratedembodiment, proximal neck 60 extends proximally for at least about the2.0 centimeter length of the support 50. Preferably, neck portion 60extends an additional 2 centimeters overlapping the tapered section 66,and as much as an additional 5 centimeters or more at 68 along thelength of tubular body 12. The proximal neck portion 60 is convenientlysecured such as by heat shrinking, as will be understood in the art.

In one embodiment of the invention, both the tubular body 12 and theballoon 28 comprise crosslinked medium density polyethylene. As aconsequence, the heat shrunk proximal neck 60 does not form a strongbond with the wall adjacent thereto. In order to prevent the pressure ofthe inflated balloon 28 from peeling the proximal sleeve 60 apart fromthe adjacent wall 13, an annular band 70 of non-crosslinked mediumdensity polyethylene is provided, to permit bonding of the proximalsleeve 60 to the tubular wall 13. Band 70 in one embodiment is in theform of a 0.050 inch inside diameter by 0.054 inch length annular ring.The same construction preferably is used at the distal end of theballoon as well.

In a preferred embodiment of the illustrated design, the dilatationballoon comprises a relative non-elastic material, such as mediumdensity polyethylene, linear low density polyethylene, polyethyleneteraphthalate, nylon, polyester, or any of a variety of other medicalgrade polymers known for this use in the art. Preferably, the geometry,materials and seals of the balloon 28 will withstand an internalpressure of at least about 10 atmospheres without any leakage orrupture.

Balloon 28 is preferably pre-molded to have an inflated diameter in acatheter intended for peripheral vascular applications within the rangeof from about 1.5 millimeters to about 8 millimeters. The balloon 28 ina catheter intended for coronary vascular applications preferably has aninflated diameter within the range of from about 1.5 millimeters toabout 4 millimeters.

The distal sleeve 62 of balloon 28 is heat shrunk over the distal tip ofthe catheter, and may take any of a variety of forms, depending upon thedistal tip construction.

The basic method of the present invention can be accomplished by any ofa variety of structures which permit a perfusion conduit within acatheter to be enlarged from a first, reduced cross sectional area to asecond, enlarged cross sectional area. Preferably, as has beendescribed, a support structure is provided for maintaining the perfusionlumen in the second configuration.

Referring to FIGS. 7 and 8, there is disclosed an alternative supportstructure for maintaining patency of the perfusion conduit. FIG. 7illustrates a representational view of a radially enlargable tubularsupport 72 disposed within the balloon region 74 of a dilatation and/ordrug delivery catheter 70. The radially enlargable support 72 preferablycomprises a coil having a proximal end 75, a distal end 76 and a centralflow passageway 77 extending axially therethrough. The support member 72may therefore be radially reduced or enlarged by rotating one end of thecoil relative to the other, as will be understood by one of skill in theart.

The construction and design details of the catheter illustratedschematically in FIGS. 7 and 8 is in many ways similar to the embodimentillustrated in FIG. 6. However, rather than axial movability of thesupport structure 50 illustrated in FIG. 6, the support structure 72 ofFIGS. 7 and 8 is preferably permanently positioned within the inflationballoon 74. In one embodiment, the proximal end of the support structure72 is secured against rotation with respect to the catheter body. Thedistal end of the support structure 72 is secured to a rotatable wirewhich extends axially throughout the length of the catheter to aproximal source of rotational energy. Rotation of the wire causes aradial enlargement or reduction of the profile of the catheter beneaththe balloon 74.

The source of rotational energy can either be a finger manipulablewheel, or other structure for permitting rotation of the wire, eitherdirectly, or through a gear train to provide a rotational advantage atthe distal end.

Prior to installation of the support member 72, an outer tubular sleeveis preferably heat shrunk over the loops of the coil, while the coil inits radially enlarged configuration. The coil is thereafter converted toits reduced profile, for installation and positioning of the catheter.In one embodiment, the native diameter of the coil is the reduceddiameter as illustrated in FIG. 7. In this embodiment, a rotationalforce is required to wind the spring up to its enlarged diameterconfiguration. Alternatively, the native diameter of the coil is theenlarged flow capacity configuration, so that the coil may be wound downto its reduced profile for insertion, and then released so that itreturns to its enlarged cross sectional area configuration under its ownforce.

Referring to FIG. 9, there is disclosed an elongate tubular drugdelivery and balloon dilatation catheter 80 in accordance with a furtheraspect of the present invention. The catheter 80 generally comprises atubular body 102 having a distal functional end 82, and a proximalcontrol end 84.

Distal end 82 generally comprises a distal tip assembly 86, disposeddistally of a combination inflation and drug delivery balloon assembly88. Distal tip assembly 86 is provided with a tip as previouslydiscussed, and a plurality of perfusion ports 126. Proximal to theballoon assembly 88 is an influent region 90, which is preferably alsoadapted to receive a movable support when the catheter is in aninsertion mode, as has been previously discussed.

Proximal end 84 generally comprises a manifold 92, having a guidewirelumen access port 94 thereon. In addition, an inflation port 96 isprovided for allowing fluid communication with the inflation balloon120. An infusion port 98 is also provided, for permitting infusion of agas or fluid such as a medication to be delivered through the distal end82 of the catheter.

A control 100 is mounted on the catheter body 102, for controlling theaxial position of the movable support as has been discussed inconnection with previous embodiments.

As illustrated in FIG. 10, the tubular body 102 is provided with anaxially extending guidewire lumen 104, for conducting a guidewirethrough the catheter body and out the distal end as has been discussed.Although the drug delivery catheter 80 illustrated in FIG. 9 is an overthe wire embodiment, the catheter can be readily converted to a monorailembodiment by one of skill in the art.

In a monorail type exchangeable catheter embodiment, an access port (notillustrated) is provided along the tubular body 102 in between theinfluent region 90 and the manifold 92. That access port provides accessthrough the wall of the tubular body 102 and into guidewire lumen 104 asis known in the art. Preferably, the access port is positioned withinthe range of from about 10 cm to about 40 cm from the distal tip of thecatheter.

In a monorail embodiment, the portion of the guidewire lumen 104disposed proximally of the access port is preferably filled with astiffening rod, or polymer, as has been discussed, to improve thepushability and other physical properties of the catheter body.Alternatively, the tubular body 102 can be extruded in a manner thateliminates the portion of the guidewire lumen 104 disposed proximally ofthe monorail guidewire access port.

A balloon inflation lumen 106 extends axially through the tubular bodyfor providing fluid communication between the balloon inflation port 96and the inflation balloon 120 as will be discussed. In addition, aninfusion lumen 108 extends axially through the tubular body 102, forproviding fluid communication between the infusion port 98 and one ormore drug delivery ports 126 disposed on the distal portion 82 of thecatheter 80.

An axially extending push wire lumen 110 is provided for axially movablyreceiving the push wire 112. Push wire 112 mechanically links thecontrol 100 with the movable support, as has been discussed in previousembodiments.

Referring to FIG. 11, a central perfusion lumen 114 is defined withincollapsible tubular wall 118, surrounding the support 116. Althoughillustrated in FIG. 12 in an enlarged configuration, the tubular wall118 will normally be partially or completely collapsed when the support116 is in the proximal insertion position. In the illustratedembodiment, patency of the perfusion lumen 114 is restored and/ormaintained by advancing the support 116 distally into the perfusionposition. Patency of the perfusion lumen can also be optimized usingalternate support structures such as a radially expandable structure ofthe type illustrated in FIG. 7 and 8.

An inflatable balloon 120, illustrated in the inflated position, isdisposed within an outer delivery balloon 122. Inflatable balloon 120and delivery balloon 122 will be described in detail infra. The deliveryballoon 122 is supplied with a media to be delivered such as a fluidmedication by way of infusion lumen 108 and a delivery lumen 124extending between the inflation balloon 120 and delivery 122. See FIGS.11 through 13.

In a preferred embodiment of the illustrated design, the inflationballoon comprises a relatively nonelastic material such as linear lowdensity polyethylene, polyethyleneteraphthalate, nylon, polyester, orany of a variety of other medical grade polymers known for this use inthe art. Preferably, the geometry, material and seals of balloon 30 willwithstand an internal pressure of at least about 5 atmospheres for drugdelivery applications, and, preferably at least about 10 atmospheres fordilation and drug delivery applications, without any leakage or rupture.

Balloon 120 is preferably premolded to have the same inflated diametersas discussed in connection with previous embodiments. Constructionmaterials and other design parameters can be readily modified by one ofordinary skill in the art, depending upon the intended use of thecatheter. In particular, balloon 120 can be constructed in a manner thatis suitable for use in dilatation procedures, such as is well known inthe art of percutaneous transluminal coronary angioplasty and otherapplications in which dilatation of stenotic region in a body lumen isdesired. Alternatively, the balloon 120 may merely be desired to providesufficient radially expansive force to compress the drug deliveryballoon 122 against the wall of the vessel. In this intended useembodiment, considerations appropriate for a lower pressure system maybe utilized.

The drug delivery balloon 122 is most conveniently disposed radiallyoutwardly from the inflation balloon 120. Drug delivery balloon 122 maycomprise a generally nonelastic material such as is conventional forangioplasty dilatation balloons, or may alternatively comprise anelastic material such as latex or urethane, or any of a variety of othersuitably biocompatible elastomers. Use of an elastic material for drugdelivery balloon 122 can assist in reducing the relatively rough edgesof the collapsed inflation balloon 120, and thereby reduce trauma to thevascular intima during insertion and withdrawal of the catheter.

Drug delivery balloon 122 is provided with a plurality of delivery ports126. Delivery ports 126 may be disposed radially symmetrically about theouter periphery of the delivery balloon 122, or may be limited to onlyportions of the exterior surface of the delivery balloon 122 dependingupon the desired drug delivery pattern. For example, delivery ports 126can be positioned along a single line extending axially along theballoon, or on one hemisphere of balloon 122. Alternatively, deliveryports 126 can extend for less than the entire length of the balloon.

Delivery balloon 122 alternatively comprises a material which isinherently permeable, without the provision of discrete delivery ports126. For example, woven or braided filaments or fabrics can be used. Forrelatively low delivery rate applications, fluid permeable membranes canalso be used.

As can be seen with reference to FIGS. 9 through 12, drug or other fluidintroduced through infusion port 98 is conducted by way of infusionlumen 108 and 124 into the interior of drug delivery balloon 122. Theinflated volume of inflation balloon 120 causes the drug to be expelledby way of ports 126 outside of the drug delivery system.

Preferably, the relative inflated dimensions of the delivery balloon 122and the inflation balloon 120 are such that a minimum amount of drug isretained between the two balloons. Thus, preferably, the inflatedinflation balloon 120 substantially completely fills the interiorchamber of the drug delivery balloon 122 to efficiently expelessentially all of the fluid introduced into balloon 122 by way of drugdelivery lumen 108. Residual volume of drugs contained in lumens 108 and124 can be expelled outside of the balloon 122 such as by following thedrug with a small volume of normal saline or other "rinse" solution, aswill be understood by one of skill in the art.

In a further alternative, the inflation and drug delivery areaccomplished by the same balloon. In this embodiment, the permeabilityrate of the balloon material, or the diameter and number of deliveryports 126 are sufficiently small that the balloon 122 is sufficientlyfirmly inflated without delivery at an excessive rate. Appropriatepermeability rates for the balloon material can be determined throughroutine experimentation, in view of such factors as the viscosity of thedrug, desired delivery rate, and the desired radially expansive force tobe exerted by the balloon.

The catheter 80 can be manufactured in accordance with the techniquesdescribed in connection with previous embodiments, with the outerdelivery balloon heat shrunk or otherwise positioned over the inflationballoon. The inflation balloon can be manufactured in any of a varietyof manners which are now conventional in the art, such as free-blowingpolyethylene, polyethyleneteraphthalate, nylon, polyester, or any of avariety of medical grade polymers known for this use.

Generally, the delivery balloon is produced by blowing sections ofcross-linked polyethylene within a tubular mold to control the outsidediameter. The outside diameter of the section is generally within therange of from about 1.5 mm to about 5.0 mm for use on a 0.042 inchdiameter catheter body.

The section of delivery balloon material is thereafter heat stretched atthe proximal and distal necks down to a thickness of about 0.001 inchesand a diameter which relatively closely fits the portion of the catheterbody to which it is to be sealed. The appropriate length is cut,depending upon the desired length of the balloon and balloon deliveryregion, and the desired balloon neck length in the finished product.

The proximal neck is heat sealed around the catheter body 102 andinflation balloon 120. In general, the length of the proximal neck ofthe delivery balloon is within the range of from about 1 cm to about 5cm inches, or longer, depending upon desired flexibility and othercharacteristics. The delivery lumen 124 is formed by placing a mandrelin between the two balloons prior to the final heat shrinking step ofthe proximal neck portion, and thereafter removing the mandrel followingthe heat shrinking step. The distal neck is thereafter heat shrank tothe desired configuration.

In an embodiment utilizing cross-linked polyethylene for both the innerinflation balloon and outer delivery balloon, the delivery balloon maybe secured to the axial ends of the inflation balloon through the use ofa UV curable adhesive, due to the difficulty in thermally bondingcross-linked polyethylene to cross-lengthened polyethylene.

However, it is to be understood that the material utilized for the outerdelivery balloon may be varied considerably, and the term balloon asused in the context of the delivery "balloon" 122 is intended to be onlygenerally descriptive of this structure as has been discussed.

Referring to FIG. 12, the inflation balloon 120 and delivery balloon 122are secured together in at least a sufficient manner to permit thedeflation of inflation balloon 120 such as by aspiration to pull thedelivery balloon 122 into a retracted profile. This is accomplished inthe illustrated embodiment by securing portions of the inflation balloon120 to the delivery balloon 122 such as in the region between a distalpoint of attachment 130 and an intermediate point of attachment 132.

In addition, a proximal zone of the delivery balloon is also preferablysecured to the inflation balloon such as between an intermediate point134 and proximal point of attachment to the catheter body 136. Thisconstruction leaves a delivery zone of at least that region on thedelivery balloon between points 132 and 134. The width of this deliveryzone can be increased or decreased as desired, depending upon thedesired delivery profile.

In an embodiment having a balloon length of about 2.6 cm from point 130to point 136, the delivery zone (132 to 134) will normally be about 1 cmin length. In addition, alternate structures such as adhesive bands,spot seals, welds, or other manners known to those of skill in the artcan be utilized to cause the outer delivery balloon 122 to reduce inprofile in response to the aspiration of inflation balloon 120.

Referring to FIGS. 14 and 15, there is shown an embodiment of adilatation and perfusion catheter design having an alternate tip design.The embodiment of FIGS. 14 and 15 can be readily modified toadditionally include a drug delivery capability in accordance with thedisclosure herein by one of skill in the art.

Referring to FIG. 14, there is disclosed an inflation and perfusioncatheter 140, having an inflatable balloon 142 shown in the deflated,low profile configuration. The principal difference between thisembodiment and that disclosed in FIGS. 4 through 6 occurs in theperfusion segment 144.

The perfusion segment 37 in FIGS. 4 through 6 is illustrated as having adiameter which is unchanged between the insertion configuration of thecatheter and the perfusion configuration of the catheter. However, theperfusion segment 37 in this design can become the perfusion flow ratelimiting structure when the catheter is in the perfusion position. Thealternate tip design of FIGS. 14 and 15 permit a perfusion segment 144to change between a low profile, insertion configuration shown in FIG.14, and an enlarged, increased fluid flow capacity configuration asshown in FIG. 15 for maximum perfusion.

The collapsible perfusion segment 144 can be constructed in any of avariety of ways and accomplish the optimized perfusion advantage of thepresent invention. In the embodiment illustrated in FIG. 15, thematerial of balloon 142 extends in the form of an elongated distal neck146 which is preferably reduced by taper 148 to form an introductionsegment 150 as has been described. The wall 146 of perfusion segment 144exhibits a similar flexibility to the wall of balloon 142. Perfusionsegment 144 is additionally provided with a plurality of perfusionopenings 152 for communicating with a plurality of perfusion openings154 by way of a central lumen 156 as has been described in connectionwith previous embodiments.

The illustrated embodiment is provided with an axially movable support160, illustrated in the form of a spring coil. The support 160 ispreferably capable of extending a sufficient distance into the perfusionsegment 144 to open the interior lumen of the perfusion segment 144 whenthe support 160 is advanced into the distal position. The distalextension of the support 160 may take a variety of forms, such as anextension of the spring coil beyond the distal end of the balloon 142.

Alternatively, as illustrated in FIGS. 14 and 15, a distal leadersegment 158 is provided. Leader segment 158 preferably comprises a solidwall tubular member, such as a section of polymeric extrusion or shrinkwrap tubing, which is secured to the distal end of the spring coil by anouter shrink wrap tubing layer 162. Preferably, the leader segment 158is provided with a wedge shaped distal tip 159, to facilitate openingthe central lumen within the perfusion segment 144 upon distalrepositioning of the support member 160. A variety of other leadersegments for maintaining patency of the perfusion segment 144 can beconstructed which will accomplish the function achieved by the presentinvention. Thus, for example, two-piece or one-piece integral supportstructure 160 and leader segment 158 can be readily constructed in avariety of configurations. Advantageously, this embodiment permits aminimal profile for both the balloon segment and the distal perfusionsegment 144 for insertion of the catheter into a small opening, yetpermits maximum perfusion therethrough when the catheter is moved to theperfusion configuration.

In accordance with a method of the present invention, a site isidentified in a body lumen where it is desired to deliver an amount of amedication or other fluid. For example, thrombolytic or restenosisinhibiting drugs may be desirably introduced directly to the affectedwall following dilatation. Alternatively, anticoagulants, plaquesoftening agents or other drugs may be desirably delivered directly tothe site of a thrombosis or other vascular anomaly.

A conventional angioplasty guidewire is percutaneously transluminallyinserted and advanced to the desired treatment site. Guidewires suitablefor this purpose are commercially available, having a variety ofdiameters such as 0.014 inches.

The distal end of any of the catheters disclosed herein is threaded overthe proximal end of the guidewire, once the guidewire has beenpositioned within the desired delivery site. The catheter is thereafteradvanced distally along the guidewire in a conventional manner, untilthe drug delivery balloon 122 is disposed adjacent the desired deliverysite. Thereafter, a suitable inflation fluid such as a radiopaquesolution is introduced by way of inflation port 96 and into theinflation balloon 120 to press the delivery balloon 122 against thevascular wall. As described previously herein, the catheter of thepresent invention may additionally be used to perform dilatation, ifdesired.

Either prior to, during or following dilatation of inflation balloon120, the tubular support structure 116 is preferably positioned tomaintain or restore patency to central lumen 114. In the illustratedembodiment, for example, this is accomplished by moving the tubularsupport structure 116 distally to a perfusion position within theinflation balloon 120.

Once the drug delivery balloon 122 has been positioned adjacent thevascular wall, and the tubular support structure 116 positioned withinthe central lumen 114, medication is infused for expulsion by way ofdrug delivery ports 126 directly against the vascular wall. Medicationcan be introduced under gravity feed alone, or by way of a pressurepump, as desired by the clinician in view of such factors as drugviscosity, toxicity and desired delivery rate.

In this manner, drugs can be permitted to be absorbed into the affectedsite, with a minimal amount drug escaping into generalized circulation.At the same time, perfusion beyond the delivery balloon is optimized byway of the central lumen 114.

The rate of drug delivery is somewhat limited by the rate of absorptionby the vascular wall, and delivery rates on the order of about 30 ml perhour to about 20 ml per minute are presently contemplated for use in themethod of the present invention. Certain medications may be optimallydelivered at much lower rates, as well, such 1 ml per day or lower.However, these rates may be modified significantly, depending upon thedrug, and the extend to which "overflow" fluid is permitted to escapeinto the circulatory system.

In either the balloon dilation or the drug delivery applications, thecatheter may desirably remain indwelling and inflated for an extendedperiod of time. Perfusion past the inflation balloon by way of atemporary stent of the type disclosed herein minimizes the adverseimpact on circulation due to the indwelling catheter. Following infusionof the predetermined volume of drug, or the desirable dilatation periodand/or post dilatation period, the balloon may be deflated and thecatheter proximally withdrawn from the treatment site in a conventionalmanner. Generally, there is no need to return the tubular supportstructure 116 or 50 to the proximal insertion position in order toaccomplish removal of the catheter.

The basic methodology for use of the present invention in a balloondilatation procedure, or a post-dilatation treatment include the stepsof positioning the balloon within the treatment site, while the tubularsupport structure is in the insertion position, thereafter advancing thetubular support structure distally into the perfusion position.Alternatively, the tubular support structure is enlarged radiallyoutwardly or otherwise moved from the insertion position to theperfusion position depending upon the structure of the tubular supportstructure.

Thereafter, the inflation balloon is inflated or permitted to remaininflated for a sufficient balloon dilatation or post-dilatation period.The inflation balloon is subsequently deflated, and the catheter isremoved in accordance with conventionally techniques.

Although this invention has been described in terms of certain preferredembodiments, other embodiments that are apparent to those of ordinaryskill of art are also within the scope of the invention. Accordingly,the scope of the invention is intended to be defined only by referenceto the appended claims.

What is claimed is:
 1. A drug delivery catheter, comprising:an elongate,flexible tubular body; an inflatable drug delivery balloon on thetubular body; at least one influent port on the tubular body on a firstside of the balloon; at least one effluent port on the tubular body on asecond side of the balloon, said influent and effluent ports in fluidcommunication with each other by way of a central lumen through theballoon; and an axially movable support within the central lumen, saidsupport movable from a first, proximal position to a second, distalposition, wherein at least a portion of the central lumen has a firstinside cross-sectional flow area when the support is in the proximalposition and a second, larger inside cross-sectional flow area when thesupport is in the distal position.
 2. A catheter as in claim 1, whereinsaid support comprises a spring coil.
 3. A catheter as in claim 1,further comprising an axially movable push wire extending through thecatheter for moving the support from the proximal position to the distalposition.
 4. A balloon catheter as in claim 1, further comprising anelongate guidewire lumen extending through said tubular body.
 5. Acatheter as in claim 4, further comprising an access port on the side ofthe tubular body for providing access to the guide wire lumen, saidaccess port being located on the first side of the balloon.
 6. A ballooncatheter as in claim 4, further comprising a port on the proximal end ofthe tubular body for accessing the guidewire lumen to provide anover-the-wire catheter.
 7. A catheter as in claim 1, further comprisingan inflation balloon disposed within the delivery balloon.
 8. A catheteras in claim 7, wherein at least a portion of the delivery balloon issecured to the inflation balloon so that the profile of the deliveryballoon is reduced in response to a reduction in profile of theinflation balloon.
 9. A catheter, comprising:an elongate, flexible,tubular body; a drug delivery balloon on the tubular body; at least oneinfluent port on the tubular body on a first side of the balloon; atleast one effluent port on the tubular body on a second side of theballoon, said first and second ports in fluid communication with eachother by way of a central lumen through the balloon; and a movablesupport within the central lumen, said support movable from a first,reduced diameter to a second, enlarged diameter.
 10. A catheter as inclaim 9, wherein said support comprises a spring coil.
 11. A catheter asin claim 10, wherein said support is movable from the first to thesecond diameter by relative rotation of one end of the coil with respectto the other end of the coil.
 12. A catheter as in claim 9 wherein saidballoon comprises a plurality of perforations.
 13. A drug delivery,perfusion and dilatation catheter, comprising:an elongate, flexibletubular body; an inflatable dilatation balloon on the tubular body; adrug delivery balloon on the tubular body, disposed about the dilatationballoon; at least one influent port on the tubular body on a first sideof the dilatation balloon; at least one effluent port on the tubularbody on a second side of the dilatation balloon, said influent andeffluent ports in fluid communication with each other by way of acentral lumen through the balloon; and a movable support within thecentral lumen, said support movable from a first position in which thecentral lumen has a, reduced flow capacity to a second position in whichthe central lumen has an enlarged flow capacity.